Method of stabilizing belt edge yarns

ABSTRACT

The raw edges of a belt having an elastomeric carcass encasing one or more fabric mats are stabilized by treating the edges with a low viscosity, quick hardening adhesive which is quickly wicked into the fabric cords or yarns in the region of the edge and hardens within a few seconds so as to form a durable bond between adjacent yarns and between the yarns and the elastomeric carcass.

FIELD OF THE INVENTION

The present invention relates to belting, and more particularly relates to treating the edges of belting to minimize fraying, with bale-forming belts being of particular interest.

BACKGROUND OF THE INVENTION

Bale-forming belts of large round balers are typically cut from slabs of elastomeric material containing one or more fabric mats including warp and fill cords which respectively extend lengthwise and crosswise in the belt. These belts have failures involving loose yarns at the edges of the belts which cause unsightly fraying, loss of belt strength, and perception of poor belt quality. In some severe cases, loose yarns have been known to become wrapped or entangled in the rollers, bearings or other machine components causing damage to, or failure of these components.

Some known solutions to the loose yarn problem have been to either mold rubber onto the edges of the belt as it is produced, or to brush on some type of coating such as a urethane or rubber coating to try to seal the belt edge. Both solutions are expensive and time consuming. Molded rubber edges generally require belts to be formed individually which is a slow process compared to molding belting material in the form of wide slabs and then slitting narrow belts from the belting slab. Brush-on coatings used heretofore have been difficult to apply and take significant time to dry, as they are normally made from a mixture of base urethane, rubber, etc., and a solvent which must evaporate for a considerable time before the belt can be handled or used. Also, the durability of the belt edges covered in these ways has not been entirely satisfactory, with the brush on solutions in particular showing a tendency to wear away quickly or peel off from insufficient adhesion when the belts occasionally contact or rub against belt guides or other adjacent structure including walls or the like.

The problem to be solved then is to provide a relatively inexpensive and durable way to stabilize the yarns at the edge of a belt without appreciably slowing the process of manufacturing the belts.

SUMMARY OF THE INVENTION

According to the present invention there is provided a novel belt edge treatment for stabilizing the yarns contained in the belt.

An object of the invention is to provide a belt edge treatment which is a solution to the above-noted problem. This solution is achieved by applying a small amount of low viscosity, quick setting adhesive to the raw edge of a belt that has just been cut from a formed belting slab.

This and other objects will become apparent from a reading of the ensuring description together with the appended drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view showing a belting slab being slit into individual bale-forming belts.

FIG. 2 is a schematic perspective view showing one of the belts of FIG. 1 being fed through a station for treating one side edge with an adhesive for stabilizing the yarns in that side.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to FIG. 1, there is shown a cutting or slitting station 10 used in the manufacture of belts used for forming bales in a large round baler. The station 10 includes a support table 12 to which a horizontal knife support 14 is fixed. A plurality of knives 16 are fixed to and project vertically from the knife support 14 at locations spaced apart by a distance equal to that of a desired finished belt width. A belt material hold-down roll 18 extends parallel to, and is located just downstream from, the knife support 14. The roll 18 is mounted for rotation about a shaft 20 having its opposite ends down-turned and projecting vertically through the table 12. Coil compression springs 22 are received on sections of the down-turned ends of the shaft 20 extending beneath the table 12 and act between an underside location of the table 12 and respective stops carried by down-turned ends of the shaft 20 so as to bias the roll 18 towards the top of the table 12.

The knives 16 are shown in the process of slitting a belting material 24, previously molded as a relatively wide slab, to obtain a plurality of belts 26 from the belting material 24, which has been stored on a cylindrical drum 28 having closed ends through which a center support shaft 30 extends, with the shaft 30 having its opposite ends supported for rotation by bearings 32 carried by a support stand 34. The drum 28 rotates as it pays out the belting material 24 during the slitting process, as will be described more fully below. As shown, a middle section 36 of the belting material 24 extends from the first drum 28, over the table 12 and is joined to a right end section 38 of the belting material 24 that is wrapped about a second or take-up drum 40 having closed ends. The drum 40 can be made of wood, or the like. Each drum end contains a central opening shaped complementary to, and receiving a square drive shaft 44 supported at its opposite end regions for rotation by a bearing 46 carried by a support stand 48. A drive motor 50, is coupled for driving the shaft 44. The motor 50 is preferably a hydraulic motor, but other types of motors could be used.

Prior to reaching the stage of the slitting process illustrated in FIG. 1, all of the belting material 24 was wrapped about the drum 28 and the drum 28 was placed on the support stand 28. The take-up drum 40 was placed on the support stand 48 and a length of the belting material 24 was pulled from the drum 28 and placed over the knives 16 and beneath the hold-down roller 18. Screws or other fasteners were used to secure a free end of the belting material 24 to the cylindrical central section of the drum 40. Next, slits were made in the belting material 24 for the reception of the knives 16 and the belting material 24 placed onto the knives 16. Once the knives 16 were in place in the slits, the motor 50 was operated so as to pull the belting material 24 against the knives 16, thereby creating elongate slits in the belting material 24 resulting the production of the belts 26. In the example illustrated, five belts 26 are created, with each end knife 16 being used to trim narrow portions from opposite sides of the belting material 24. Therefore, similar raw edges 52 are formed at opposite sides of each of the belts 26. Fabric cords, not shown, contained in the construction of the molded belt material 24 are exposed at these raw edges.

Referring now to FIG. 2, there is shown an adhesive application station 54 including a support table 56. A vertical pay-out spindle 58, constructed of a vertical tube, is mounted to the support stand 56 for rotation by a bearing (not shown) carried at a leftward location by the stand. A drag mechanism 60, such as a brake, is selectively engaged with an interior surface of the spindle 58, for a purpose explained below. Received on the spindle 58 is a first spool 62 on which is coiled a first section 64 of one of the baler belts 26. A vertical take-up spindle 66, similar to the spindle 58, is mounted to the support stand 57 for rotation by a bearing (not shown) carried at a rightward location by the table. Received on the take-up spindle 66 is a second spool 68 on which is coiled a second section 70 of the baler belt 26. A torque limited motor 72 is coupled to a lower end of the take-up spindle 66, for a purpose to be explained. A middle section 74 of the baler belt 26 joins the first and second sections 64 and 70 of the belt 26 and rests on the support table 56. Fixed to the support table 56 and engaged with opposite surfaces of the middle section 74 of the belt 26 are a pair of vertical guide plates 76 and 78. Located in engagement with one surface of the belt middle section 74, and on opposite sides of guide plate 76 are a pair of belt drive rolls 80 and 82, respectively. Located in engagement with the opposite surface of the belt middle section 74 directly opposite from the drive rolls 78 and 80 are a pair of pressure rolls 84 and 86, which are spring loaded, in a conventional manner, not shown, toward the drive rolls 78 and 80. A first drive motor 88 is coupled for driving the roll 80 and a second drive motor 90 is provided for driving the roll 82. The drive motors 88 and 90 may be variable speed hydraulic motors, with the downstream motor 90 being driven at a speed slightly faster than the motor 88 so that the belt segment located between the two motors is kept taut, for a purpose explained below. It is here noted that the torque limited motor 72, which drives the take-up spindle 66, would operate so as to cause the belt 26 to be tightly coiled about the take-up spindle 66 without causing any increase in the speed that the belt 26 is driven by the downstream motor 90.

An adhesive delivery system 92 includes a pump 94, which may be driven in any known manner to result in adhesive being delivered at a constant rate. The pump 94 has its intake coupled to an adhesive supply reservoir 96 and its output coupled, by way of a conduit 98, to a tapered nozzle 100 mounted, as by an articulated link 104, to an upper end section of a standard 102 fixed to the guide plate 78 so that the nozzle 100 is located in close proximity to an upper raw edge 52 of the belt 26. Loosening the joints of the articulated link 104 permits the nozzle 100 to be pivoted out of the way so as to not interfere with the placement of the belt 26 within the respective nips defined by the drive roll 80 and pressure roll 84, and by the drive roll 82 and pressure roll 86. The taut belt segment extending between the drive rolls 80 and 82, due to the differential in speed of the motors 88 and 90, always remains upright so that the edge 52 is always properly positioned for receiving the adhesive dispensed from the nozzle 100. Since the adhesive is delivered at a constant rate, the downstream drive motor 90 is driven at a constant speed which correlates with the delivery rate of adhesive so as to cause the correct amount of adhesive to be deposited on the belt edge 52. An appropriate control system, including optical sensors, for example, is provided for automatically shutting off the adhesive pump 94 when it is sensed that the end of the belt 26 is approaching the nozzle 100.

The operation of slitting the molded belting material 24 so as to form baler belts 26 having raw edges 52 is thought evident from the foregoing and no further description of the operation is given.

In applying adhesive to the belt edges 52, as shown in FIG. 2, the station 54 is readied by placing the spool 62, which has a baler belt 26 coiled thereabout, on the pay-out spindle 58. A length of the baler belt 26 is then pulled off the spool 62 and fed between the first set of rolls 80 and 84, between the guide plates 76 and 78, and finally between the second set of rolls 82 and 86. The pulled off length of the belt 26 is then wrapped a sufficient amount about the spool 68, which resides on the take-up spindle 66. The adhesive dispensing nozzle 100, which up to this point will have pivoted to a location so as to not interfere with the placement of the belt 26, is pivoted back into place with its dispensing end closely adjacent the upper raw edge 52 of the baler belt 26. The torque limited motor 72 is then energized, but will have no ability to advance the belt 26 beneath the nozzle 100. The adhesive pump 94 and the drive motors 88 and 90 are simultaneously started so that the belt 26 will begin to be pulled beneath the nozzle 100 by the action of the drive motor 90, with the motor 88 being driven at a speed slightly less than that of the drive motor 90 so as to create a tension in the length of belt 26 extending between the motors 88 and 90, resulting in this length of belt being upright so as to be positioned correctly for the application of adhesive. The rate of application of the adhesive to the moving belt edge 52 is governed by the speed of the drive motor 90 and by the constant delivery of the adhesive pump 94. In order to maintain a slight tension in the section of the belt 26 extending from the spool 62 to the drive motor 88, a slight drag is applied to the pay-out spindle 58 by the drag mechanism 60.

Once the entire length of the belt 26, remaining downstream of the nozzle 100 when the belt 26 is initially engaged with spool 68, has been removed from the spool 62, an optical sensor (not shown), for example, will send a signal for shutting off the adhesive pump 94. The take-up spindle drive motor 72 will act to complete the wrapping of the spool 68 with the remaining portion of the belt 26. The empty spool 62 is then removed from the pay-out spindle 58, and the loaded spool 62 is inverted and placed on the pay-out spindle 58, with the empty spool then being placed on the take-up spindle 66. The joints of the link 104 are loosened and the nozzle 100 pivoted out of the way so as to permit the belt 26 to be inserted between the rolls 80 and 84, between the guide plates 76 and 78 and between the rolls 82 and 86, etc. so as to be prepared for the application of adhesive to its untreated raw edge 52 in the same manner described above. It is apparent that relatively short lengths of the edges 52 possibly will not be treated with adhesive in the described operation, however, if needed adhesive is manually applied to such areas so as to complete the edge treating process.

While FIG. 2 shows an arrangement where the belt 26 is vertical and adhesive is applied to only one raw edge 52 during one passage of the belt, other orientations of the belt 26 are thought possible, including a horizontal orientation wherein two adhesive dispensing nozzles 100 may be placed at opposite sides of the belt so as to simultaneously apply adhesive to the raw edges 52 at the opposite sides of the belt 26.

Critical to the present invention is the selection of the proper adhesive. It has been found that a small amount of cyanoacrylate adhesive, commonly referred to as “super glue” is an excellent candidate for stabilizing the yarns of the fabric incorporated in the belt 26. Specifically, it has been found that low viscosity versions of cyanocrylate adhesive are particularly effective for the reasons that:

-   -   1. the adhesive quickly wicks (depths of observed wicking was         from ⅛″ to ¼″) into the fabric yarns and cures or hardens within         a few seconds;     -   2. the bond between the yarns and the remainder of the belt         carcass is very durable resulting in a virtual elimination of         fraying for a long period of time; and     -   3. the solution is cost effective in that the quick curing time         allows automation of the process without the fear of messy         handling, contamination, etc. associated with slow-drying, tacky         materials.     -   4. low profile layer does not add significantly to belt width,         and is not readily discernible.

Other adhesives which have low viscosities found to be adequate are from the family of anaerobic adhesives. In general, any quick drying adhesive having a low viscosity similar to that of water or in the range of from 1-20 cps, and which, when applied to a belt, exhibits durability when flexed and when engaging belt guides and other nearby structure during operation of the belt, would be suitable. Also, as used in this application, the term “quick drying” is intended to cover those adhesives which will dry or harden quickly in ambient air or those which can be post treated with ultra-violet rays, heat, catalyst, etc., so as to accelerate drying (curing). Such accelerants may be important with adhesives having a viscosity greater than about 10 cps.

While the present invention has been described as applying to baler belts, it should be understood that other types of belts, such as conveyor belts, for example, would also benefit from having their raw edges treated with an adhesive as described above.

Having described the preferred embodiment, it will become apparent that various modifications can be made without departing from the scope of the invention as defined in the accompanying claims. 

1. A method of treating edges of a belt containing a fabric mat having yarns exposed at said edges and prone to fraying without treatment, comprising the steps of: a) selecting a low viscosity adhesive, which hardens quickly; and b) applying said adhesive to said edges.
 2. The method of treating edges of a belt, as defined in claim 1, wherein said adhesive is selected from a type commonly called super glues.
 3. The method of treating edges of a belt, as defined in claim 1, wherein said low viscosity is in the neighborhood of the viscosity of water.
 4. The method of treating edges of a belt, as defined in claim 1, wherein said low viscosity has a value low enough to permit said adhesive to penetrate the yarns in the region of said edges to a depth of at least ⅛″ before it hardens.
 5. The method of treating edges of a belt, as defined in claim 4, wherein said adhesive is such that said yarn becomes relatively hard when combined with said yarn and provides good resistance to wear.
 6. The method of treating edges of a belt as defined in claim 1, wherein said low viscosity has a value low enough to permit said adhesive to penetrate to a depth of at least one yarn diameter before it hardens.
 7. The method of treating edges of a belt, as defined in claim 1, wherein the adhesive selected is a cyanoacrylate adhesive.
 8. The method of treating edges of a belt, as defined in claim 1, wherein the adhesive selected is an ethyl cyanocrylate adhesive.
 9. The method of treating edges of a belt, as defined in claim 1, wherein the adhesive selected is an anaerobic adhesive.
 10. The method of treating edges of a belt, as defined in claim 1, wherein the adhesive has a viscosity in the range of 1-20 cps. 